THE BLACK HILLS BEETLE. 



13 



gallery is distinguished from that of the spruce-destroying beetle by 

 its slender form and more evenly distributed side or brood mines. 



CHARACTERS OF THE INFESTED TREES (fIG. 4 AND PL. Il) . 



Trees attacked by the Black Hills beetle between July and October 

 will be indicated by the presence of pitch tubes, or sawdust borings, 

 and upon removal of the bark the young broods will be found mining 

 tln-ough the inner living layers, or the bark will be entirely killed on 

 the main trunk; but the foliage will remain green, or will be but 

 faintly faded until 

 May and June of 

 the following year, 

 when the leaves on 

 the lower branches 

 will turn yellow and 

 die. This condition 

 will rapidly extend 

 to the topmost 

 leaves, so that by 

 the time the broods 

 of maturing beetles 

 are ready to emerge 

 the foliage is yel- 

 lowish red to light 

 reddish brown in 

 color. This is the 

 stage of death called 

 "sorrel tops." 

 Later in the sum- 

 mer and during the 

 following winter, 

 after all living ex- 

 amples of the beetle 

 have emerged, the 

 foliage is dark red- 

 dish brown, called "red tops." This condition prevails during the 

 second summer after attack ; but by the third summer all, or nearly 

 all, of the leaves have fallen, which gives the tops of the dead trees a 

 blackish appearance, called "black tops." 



Beginning with freshly attacked trees during the first summer, 

 they are distinguished by the exudation of fresh wliitish or reddish 

 pitch forming small masses or tubes on the bark of the main trunk 

 or by the presence of fresh reddish sawdust-like borings lodged in 

 the loose bark and around the base of the tree. 



Fig. 3— Work of the Black Hills beetle, in inner bark of dead tree: 

 o, primary galleries; 6, larval mines; c, pupal chambers; d, exit holes. 

 Reduced about one-half. (Author's illustration.) 



